Guardian Technologies 4758, 4456 Test 61- Check High OIL Temperature Switch, Switch terminals

SECTION 4.4

DIAGNOSTIC TESTS

PART 4

DC CONTROL

the switch terminals.

a. Set a VOM to its "R x 1" scale and zero the meter.

b. Connect the VOM test leads across the switch terminals. With engine shut down, the meter should read CONTINUITY.

c. Connect Wire 86 to Wire 0 for starting purposes only. After engine starts, remove Wire 86 from Wire 0.

d. Crank and start the engine. The meter should read INFINITY.

5.Perform Steps 4a and 4b. If INFINITY is measured with the engine shutdown, replace the LOP switch.

6.Set a VOM to it’s “R x 1” scale.

a.Connect one test lead to Wire 86 (disconnected from LOP). Connect the other test lead to Pin Location 2 (Wire 86) of the J1 connector at the Circuit Board. CONTINUITY should be measured. If CONTINUITY is NOT measured, repair or replace Wire 86 between the LOP switch and the J1 Connector.

b.Connect one test lead to Wire 0 ( disconnected from LOP). Connect the other test lead to a clean frame ground. CONTINUITY should be measured. If CONTINUITY is NOT measured repair or replace Wire 0 between the LOP and and the ground terminal connection on the engine mount.

7.If the LOP switch tests good in Step 4 and oil pressure is good in Step 3 but the unit still shuts down with a LOP fault, check Wire 86 for a short to ground. Set a VOM to it’s “R x 1” scale. Disconnect the J1 Connector from the circuit board. Remove Wire 86 from the LOP switch. Connect one test lead to Wire 86. Connect the other test lead to a clean frame ground. INFINITY should be measured. If CONTINUITY is measured, repair or replace Wire 86 between the LOP switch and the J1 Connector.

RESULTS:

1.If switch tests good for Problem 9, proceed to Test 44.

2.Replace switch if it fails the test.

TEST 61- CHECK HIGH OIL TEMPERATURE

SWITCH

DISCUSSION:

If the temperature switch contacts have failed in a closed position, the engine will not crank or start. If it tries to start, it will immediately fault out on OVERTEMP. If the unit is in an overheated condition, the switch contacts will close at 284”F. This will normally occur from inadequate airflow through the generator.

PROCEDURE:

1.Verify that the engine has cooled down (engine block is cool to the touch). This will allow the contacts in the High Oil Temperature Switch to close.

2.Check the installation and area surrounding the generator. There should be at least three feet of clear area around the entire unit. Make sure that there are no obstructions preventing incoming and outgoing air.

3.Disconnect Wire 85 and Wire 0 from the High Oil Temperature Switch.

4.Set a VOM to measure resistance. Connect the test leads across the switch terminals. The meter should read INFINITY.

5.If the switch tested good in Step 4, and a true over- temperature condition has not occurred, check Wire 85 for a short to ground. Remove Connector J2 (5-pin) from the circuit board. Set the VOM to measure resistance. Connect one test lead to Wire 85 (disconnected from High Oil Temperature Switch). Connect the other test lead to a clean frame ground. INFINITY should be measured.

TESTING HIGH OIL TEMPERATURE SWITCH:

6.Remove the High Oil Temperature Switch.

7.Immerse the sensing tip of the switch in oil as shown in Figure 28, along with a suitable thermometer.

Figure 28. Testing the Oil Temperature Switch

8.Set a VOM to measure resistance. Then, connect the VOM test leads across the switch terminal and the switch body. The meter should read INFINITY.

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